This project is a study of the biological and chemical properties of exotoxin A and related macromolecular structures from Pseudomonas aeruginosa. The rod-shaped macromolecular structures contain antigenic determinants that cross-react with neutralizing antiserum to exotoxin A and resemble pyocin sheaths in their morphology. Although enzymatically inactive, a major peptide of the oligomer corresponds to an active form of the toxin by electrophoretic analysis. It is proposed to investigate the chemical structure of the organized form and its relationship to exotoxin A by peptide analysis and antigenic analysis with monoclonal antibodies produced by the hybridoma technique. The genetic relationship between exotoxin A and the macromolecular form will be studied by analysis of a series of toxin negative mutants, in vitro synthesis, and cloning of the toxin gene(s) in an appropriate host. This project is an investigation of one of the primary virulence factors of Pseudomonas strains that cause pulmonary infections in patients with Cystic Fibrosis.